It is to be understood that the present invention relates to generators as well as to motors--hence, the dynamo/motor machine designation. However, in order to obviate the arduous writing style that would result by constantly referring to both types of machines, the description that follows will most frequently be styled as pertaining to a motor, but it will be understood that the invention relates to both motors and generators. With that preamble, it can be stated that a synchronous reluctance motor is a synchronous machine that has a stator with poly-phase windings forming a plurality of poles which are similar to induction motors. The reluctance motor also includes a rotor that does not use windings or permanent magnets but does have the same number of poles as the stator. The rotor is manufactured as an anisotropic structure. That is, each pair of poles of the motor has a direction of minimum reluctance, the direct axis, and a direction of maximum reluctance, the quadrature axis.
A synchronous reluctance motor (SYR) is similar to other synchronous motors with the distinct difference of having no DC excitation. That is, the motor does not have brushes and slip rings. The stator windings of the SYR are substantially identical with those employed in poly-phase induction motors with the added advantage of efficiently operating with concentric windings which are similar to the salient pole windings used in DC motors. The rotors of the SYR are constructed to have different values of reluctance between the direct and quadrature axes. This provides an easy flux path for the direct axis as compared to the quadrature axis. The magnetic performance index ratio (direct axis to quadrature axis reluctance) affects the performance of the SYR. The higher the ratio, the better the performance of the SYR. Conventional reluctance motors exhibit a performance index ratio of approximately five (5).
By providing a rotating field in the stator windings a magnetomotive force is created in the rotor which results in an attempt to align with the magnetomotive force generated in the stator. The rotor tends to displace the direct axis of minimum reluctance until the alignment of the fields is attained resulting in the rotor being driven at a synchronous speed proportional to the rotating field in the stator. In order that the maximum power can be derived from the motor, it is desirable to maximize the ratio of the direct-to-quadrature axis reactance. This is generally accomplished by utilizing magnetic laminations alternatingly interleaved with non-magnetic and non-conducting separators inserted axially between radially extending arms. The arms are formed with a smooth, U-shaped recess therebetween, the laminations being secured within each recess. The laminations are secured in situ by means of radial fasteners and end caps. The end caps are cup-shaped members with an axially extending outer rim that is disposed circumjacent the outermost periphery of the laminations. These motors will operate at higher efficiencies than induction motors and will also provide higher operating speeds.